1. Field of the Invention
The present invention relates to a lens system for forming a reduced image used in a device for reading an image of an original document, such as an image scanner, a facsimile, etc.
2. Description of the Related Art
A lens system for forming a reduced image used in an image reading device is mainly constructed of three or more glass lenses, and such a lens system is expensive. Thus, there is an increasing demand for an inexpensive lens system with high performance. Along with such a demand, a resin aspherical lens system constructed of two lenses is proposed but it presents problems, such as insufficient correction of aberration and great dependence upon temperature for reading performance.